Conventional progressive addition lenses are lenses which have an upper distance portion (‘the distance zone’), a lower near portion (‘the near zone’), and a progressive corridor (‘the intermediate zone’) therebetween which provides a gradual power progression from the distance zone to the near zone without any dividing line or prismatic jump.
Generally speaking, the dispensing of a particular progressive addition lens (hereafter referred to as a ‘progressive lens’) to a wearer involves a dispenser selecting a progressive lens design from a range of available lens designs based on certain visual requirements of the wearer. Such visual requirements may include the personal preferences of the wearer.
The selection process may involve a dispenser (or an expert system) selecting a lens design having a peripheral design which the wearer is comfortable with and thus suitable for the wearer. However, although the selected lens may have a peripheral design which is suitable for the wearer, other features (such as the zone size balance, eye path inset, corridor length) may not be optimal for the wearer's visual requirements.
Indeed, in a selection process which involves selecting a particular progressive lens design from a range of lens designs, a lens design having a suitable peripheral design together with other design features (such as, zone size balance, eye path inset and corridor length) which are related to the requirements of the wearer may not be available.
Accordingly, it would be a significant advantage if a progressive lens design was able to be dispensed to a wearer such that the selected lens design had a suitable peripheral design as well as design features which are more closely related to the requirements of the wearer, that is, a lens design having design features which have been individually customised for a wearer.
Accordingly, it is an object of the present invention to provide a method of designing a progressive lens for a wearer which includes design features which have been customised for the wearer so that the progressive lens is suitable for the visual requirements of the wearer.